Insulated electrode structure for spark plugs



W. S. THQMAS INSULATED ELECTRODE STRUCTURE FOR SPARK PLUGS FilledA Jan. 4, 1922 @www )f7/iam 72am CLS Patented Jan. 6, 1925.

UNITED STATES PATENT GFFICE WILLIAM S. THOMAS, OF LIILIDEN7 NE1L/'i7 ASSEGNOR TO THOMAS SPARK PLUG COMPANY, F llf., Nll JERSEY.

INSULATED ELECTRGDE STRUCTURE FOR SPARK PLUGS.

To @ZZ whom t may concern.'

Be it known that Ta TJILLTAM S. TrioMAs, a citizen of the United States, residing` at Linden, in the county of Union and State of New Jersey7 have invented certain new and useful Improvements in insulated Electi'ode Structures for Spark Plugs7 of which the following is a specification.

One object o-f my present invention is to 10 provide an improved. structure which will more effectively insulate a spark plug electrode and prevent the insulating means from becoming impaired by heat, products of combustion, oils or moisture; thus prolonglping the life of the plug and preventing current. leakage.

Another object is to so construct my improved electrode structure that it can beV readily manufactured and will keep comparatively cool while in use.

of said insulated electrode,

Figure 8 is a transverse section taken on the line 3-3 of Figure 1,

Figure 4 is an elevation, partly in section, of a portion of the electrode rod,

Figure 5 is an elevation of another portion of said rod, and Y i Figure 6 is an inverted plan view of a cap portion which I preferably' employ.

Referring to the drawings 7 represents an 4Q insulator body portion which can be made of porcelain or other material which is a non-conductor of electricity and which will withstand heat without becoming impaired to such extent as to interfere with its use as ,an insulator. The body portion 7 includes an annular boss or flange 8 which projects laterally therefrom and is positioned between the upper and lower ends. This boss is provided for the purpose of securing the insulator electrode within a shell or jacket not illustrated) in any suitable manner, such for example as by means previously employed for securing electrode insulators within the metallic jackets which are ordi- Application filed January 4, 19 Serial No. 528,870.

narily screwed into the cylinders of internal `combustion engines. The body portion 7 includes a stem 9 which depends below the flange 8 and an upwardly extendingportion 10 which projects above said flange 8. F ur! ther-more the body portion 7 includes a cavity 11 which is preferably cylindrical and extends downward from the top surface 12 of the portion 10 to a position having its bottom surface 18 below the flange 8 and within the stem 9. The recess 14C extends upward from the bottom surface 15 and the inner end 16 of the recess is positioned below the bottom surface 13 of the cavity 11 so as to provide a partition 17 between the bottom of the cavity and the inner end 16 of the recess. This partition has an axial hole 18 therein for a purpose hereinafter described. Tt will be understood however that the ho-le 18 is of small diameter compared to the diameter of the cavity 11 and recess 14.

An electrode rod includes two sections 19 and 20. The section 19 at its lower end includes an annular upturned iiange 21 which is spaced from the main part 22 so as to pro duce an annular channel or groove 23. Thus the flange 21 actually provides a cup open at the top surrounding the main part 22 as clearly illustrated in Figures 2 and 4. A screw threaded hole 24 extends axially upward from the bottom surface 25 of the rod section 19 and the upper end of the main part 22 of said rod section is externally screw threaded as shown at 26. The. rod section 2O includes a screw threaded portion 27 which is adapted to be projected upward from the hole 18 and engage the screw threaded hole 24 of the rod section 19; said rod section 19 being positioned within the cavity 11 with the flange 21 lowermost and it is preferable to insert a gasket or washer 28 between the surface 25 of the rod section 19 and the bottom surface 13 of the cavity 11. rod section 2O includes an angular enlargement 29 which is preferably made in the form of a nut and a washer or gasket 30 is placed over the portion 27 to abut the angular portion 29 and the inner surface 15 of the recess. The rod portion 29 also includes a depending part 31 which projects through the recess 14 and serves as the sparking part of the electrode rod. It will be noted that by turning the section 2O relative to the section 19 that pleSSure will be brought to bear upon the partition 17 and thus securely hold the rod to the bodyv por tion 7.

A mica tube 2:32 is entirely embedded within a housing or shell et glass or other vitreous material which is impervious to water, oil7 products ot combustion or gases which are encountered tor example in connection With the explosion within internal combustion engines and 'the hoi j 2ER is pre/rerably molded integ` ally zinuid the nica tube 3Q. The internal .iameter ot the liousing 82E is such as to permit the rod section if) to extend therethrough 5 the consriu ion further bei-ng such as to allori' the lower and ot' the housing to set ivithin the channel 2?, which is provided by the flange 2l and nu in par-t :'22 oi the electrode rod section 1.9. liiitliclmore the arrangement is preferably such as to allow an annular space Set to exist between the outer surface ol the housin and `the inner side Wall of the cavity il; said space extending downward from the top sur face i2 ot the body port-ion to a position below the bottom of the {la-nge S as clearly shown 'in Figure 2.

A cap oi' cover `has a depending (lange '3G adapt-ed to surround the upper part ot the portion 10 and said cap has a hole 3T through which the upper screnv threaded end 26 ot tlieelectrode rod section if) extends. The ca p VHangs 36 has grooves 38 at spaced distances apart which exl'cnd upward trom the' bottom surface 39 oi the cap to the linner surface 10rd said cap: said inner surface :being -positii:ned above the snrtace of the body portion so as to provide a space ail. Lugs 42 which depend trom the surtace i0 are adapted 'to engage the top surface r2 oi the body portion 7.

A binding nut 43 is screwed on the end Q6 of the rod section 19 and is adapted to engage the `top surface ai ot the cap. Thus or turning don'n on the nut 451k the cap `will be held iniirm contact with the ytop surface ot' the body portion T since said action -ivill be resisted 'by the angular or mit portion Q9 and `gasket '30 ot the rod section `20. It. will be noted that suoli structure as above deswibed includes a inica' tube which extends from lhe position above the flange 9 to a position be lon' the flange 8 and will be capable of inter- `c-epting any transverse attempt ot current leakage and furthermore this tube of mica is so covered that it ivrll not be affected so as to lose its good qualities as an insulating member; said vqualities only existing when the mica tube is kept tree trom contamination lWith moisture, gases. oils or products of combustion.

It Will be further noted that said structure alloWs'air to surround the housed mica tube and thus the tube `is kept ventilated and comH parati-vely cool; the air beinefree to pass between the atmosphere and the spaces 3,4-v

through the medium ot the grooves 38 and space 4:1. The parts of my improved structure can be readily assembled and disassembled. The housed mica tube can be placed within'the electrode rod section 19 bel'ore the latter is placed within the cavity ,il and it. is merely necessary to insert the part '2T of the portion 2() ot the rod upward through the hole 1S`y after which the part 20 can be rotated by inserting a small socket Wrench within the recess i4 so as to engage and rotate the nut portion 29. The cap can then be slipped over the top of the section 1%) and the nut 43 applied. ny desirable clamping nuts tor electric conduit wire can be connected to the end Q6.

lVhile l have described my invention as taking a particular torm, it will be runderstood that the various parts ot my invention ma),Y be changed Without departing from the spirit thereo7 and hence I do not limit myself to the precise construction set forth, but consideuthat I am at liberty to make Such changes and alterations as fairly come Within the scope of the appended claims.

Having thus described my invention, what I claim 4as new and desire to secure by Letters Patent` is 1. A structure ot the class described including a bod)v having a cavity formed therein, an insulating tube confined Within the cavity` an electrode rod taken through the body and through the i-nsulating'tube and having an exterior thread bearing portion. a member adapted for threaded engagement with the thread bearing exterior portion and 'having a -fiange surrounding the adjacent end portion of the body` and pro vided `with grooves in spaced relation cxtending upwardly from the bottom edge of the flange. and projections on said member adapted to rest upon the adjacent edge of the vbody supporting the member in spaced relation with res-peet thereto.

2. A structure ot' the class described including a body having a cavity, an electrode `rod extending into the cavity and comprising sections in threaded connect-ion, one of the sections having screw threads 'termed in its outer end portion. a housing having a tube of insulating material confined therein`l surrounding one of the electrode sections and supported thereby in spaced relation to the walls of the cavity, a carp for the body having portions in spaced relation with the Walls thereof and having a central Vopening for the 'passage of the threaded portion of the electrode section` .and 'a member threaded the cavity and through the cap, and a housing encasing a mica tube carried by the electrode rod in spaced relation with the Walls of the cavity.

t. A spark plug electrode structure including a body portion having a cavity; an electrode rod secured to said body portion and extending through said cavity; and a cap having a flange surrounding said body 10 portion adjacent its top and being grooved to provide an air passage between it and the body portion, said cap having lugs spaced apart to provide a space communicating with said cavity and With said grooves; substantially as described.

5. A spark plug electrode structure including a body portion having a cavity; an electrode rod secured to said body portion and extending through said cavity; a cap havinga flange surrounding said body portion adjacent its top and being grooved to provide an air passage between it and the body portion, said cap having lugs spaced apart to provide a space communicating with said cavityT and with said grooves7 said rod having a screw threaded portion extending through said cap; and a nut in engagement with said screw threaded portion adapted to hold the cap in position relatively to said body portion; substantially as described.

In testimony Whereol:` I have signed my name to this specification in the presence of a subscribing Witness.

"WILLIAM S. THOMAS. lVitness CHAs. E. Ross. 

